Use of Green Fluorescent Protein for Rapid Assessment of the Bactericidal Activity under Cold Plasma Irradiation

摘要

Bacterial inactivation by nonthermal or cold plasma is affected by many factors, yet the mechanisms have not been thoroughly clarified. Developing effective methods for rapid evaluation of bactericidal activity of cold plasma is thus crucial for not only optimizing the experimental conditions for the best sterilization effect, but also revealing the underlying mechanisms. Although conventional methods such as determination of colony-forming units are still the standard method for assessment of bacterial inactivation efficiency, they are time-consuming and cannot provide real-time measurement. In this work, green fluorescent protein (GFP) was utilized as the indicator for monitoring the bactericidal activity of cold plasma irradiation. GFP-expressing recombinant Escherichia coli was exposed to discharge plasma, and the intracellular fluorescence signal was detected with a flow cytometer. We found that the bacterial GFP fluorescence intensity decreased exponentially with plasma exposure time, and the result was in good accordance with the inactivation curve obtained by measuring colony-forming units. As such, this work demonstrates that GFP is useful for high-throughput screening assay for antimicrobial activity of nonthermal plasma irradiation.